Multistream analyzer with stream switching apparatus



RATUS June 16, 1959 D. E. LUPFER ET AL MULT ISTREAM ANALYZER WITH STREAM SWITCHING APPA Filed Sept, 10, 1954 M. mN E T N M R k VwT WL I T DE M A a; 51 3 3) an. M .9 530E nQ United States Patent Cffice 2,890,617 Patented June 16, 1959 MULTISTREAM ANALYZER WIIH STREAM SWITCHING APPARATUS Dale E. Lupfer and Ernest n. Tolin,'liartlesville, Okla, assignors to Phillips Petroleum Company, a corporation of Delaware Application September 10, 1954, Serial No. 455,120

11 Claims. (Cl. 88-14) This invention relates to analyzers. In another aspect,

each unit or column by heating coils 13a and 13b, respectively. By the action of the piston and heating medium, a stream of liquid is displaced from each column of crystalline material, and these streams of displaced llquid are Withdrawn through conduits 14a 'and 14b, re-

spectively. Melt or product streams are withdrawn from I the columns through the respective conduits 15a and 15b.

As one specific example of a separation which can be effected with the disclosed apparatus, the feed stream can include mixed isomers of xylene in the crystalline form together with a liquid, which may include ethylit relates to a method of controlling a crystal separation system.

Heretofore, considerable difficulty has been experienced in separating materials, such as isomers of xylene, particularly on a commercial scale. It has been found that these isomers can be separated by fractional crystallization but there is a problem in effecting adequate control L of the crystal separation operation, particularly where a plurality of separate separation units are operated.

In accordance with this invention, crystal separation operations are readily and efficiently controlled, even cation of T. A. Tarr, filed June 21, 1954, Serial Number 438,051, for a description of a complete fractional crystallization operation together with a discussion of various separations which can be effected by this method;

' -As will become apparent hereafter, it is contemplated that more than two crystal separation units may be utiwhere the operation takes place in a plurality of separate" separation zones. More particularly, in accordance with the principles of this invention, a single control instrument is utilized in conjunction with a plurality of separate separation units by successively feeding streams to be analyzed from the separate units to a single differential Pl refractometer wherein the refractive index of the sample is compared with that of a standard material to produce an output representative of the composition of the material being tested. Thereupon, the compositions of two or even more streams are indicated upon a single recorder chart, and the sample being analyzed is identified on the chart by forming an index mark thereon each time analysis of a different stream is initiated. Furthermore,by varying the length of the analyzing periods, the length of the trace on the recorder chart between consecutive index marks identifies the sample being analyzed during any particular period.

As will be evident from the foregoing, the control instrument is in itself novel by virtue of the marking circuits and provision for analysis periods of different duration, and such features have independent utility both in radiation analyzer instruments other than differential refractometers, and in the analysis or control, of operations other than crystal separation.

lized. Where this is done, each column or crystallization unit is operated in the manner already described, with the product being withdrawn through a conduit 15, the displaced liquid being introduced through a conduit 14 and -.the feed being introduced through a conduit 11.

In the embodiment shown, portions of the product streams passing through conduits 15 are withdrawn and fed,.in a cyclic manner, to a differential refractometer of novel construction. To this end, the conduits 15a, 15b are provided with restrictions 16a and 16b, respectively, which are bypassed by lines 17a and 17b, respectively. Branching from the bypass lines are two sample inlet pipes or conduits 18a and 18b, respectively, which lead to a common sample inlet pipe 19. The pipe 19 leads to a sample cell 20a of a cell assembly 20, and the sample fluid, after passing through the cell, is withdrawn through a line 21. A standard fluid is introduced through a line 22 to a standardcell 20b of the assembly 20, and standard material is withdrawn from the cell through a line 23. The pressures in the two cells are equalized in any suitable manner, for example, by the pressure equalization device shown in the copending application of Bill I. Simmons, S.N. 264,515, filed January 2, 1952, now

Patent No. 2,705,254.

Accordingly, it is an object of the invention to provide a radiation analyzer of improved character.

It is a further object to provide a method of controlling a crystal separation operation, particularly where the operation is carried out in a plurality of separate and distinct separation units.

Various other objects, advantages and features of the invention will become apparent from the following detailed description taken in conjunction with the accompanying drawings, in Which:

Figure 1 is a schematic diagram of an analyzer constructed in accordance with the invention as applied to the control of a crystal separation operation; and

Figure 2 is a view of a recorder chart. Referring now to the drawing in detail, and particularly Figure 1, we have shown a pair 10a, 10b of crystal separation units to which a feed stream including liquid and crystalline material is fed through conduits 11 and 11b, respectively. In each unit 10, a column ofcrystalline material is subjected to the action of a reciprocating piston 12a or 12b, and heat is supplied to the bottom of A beam of radiation is produced by a source 24 which is energized from terminals 24a under the control of a switch 24b. Where the instrument is a differential refractometer, as shown, source 24 can be an incandescent 'lamp-emitting radiationin the visible wavelength range.

The source 24, therefore, produces a radiation beam which passes through sample cell 20a and standard cell 20b to a rotatable reflector assembly 25 where it is reflected by prisms 25a, 25b and, thence, passes through a stationary prism 26 to a radiation detector unit 27 consisting of a pair of photoelectric cells 27a and 27b.

The action of the prism 26 is to direct a portion of the beam upon both the photoelectric cells 27, and the refiector assembly 25 moves, in the manner hereinafter explained, so as to deflect the beam and cause it to fall equally upon the two photoelectric cells. ,The beam deflection thereby produced balances the deflection produced as the beam passes through the material in cells 20a and 20b by virtue of the difference in the refractive indices of the fluids contained therein. That is, the amount of rotation of assembly 25 necessary to provide a balance of the radiation incident upon the photoelectric cells is representative of the difference in refractive inphotomultiplier tube is a dices of the test and standard materials and,.. hence, of

the composition of the test material.

As will become apparent hereafter, the principles of -.the invention are applicable to radiation analyzers 'other than differential refractometers. Where other such "in- .flstruments were used, source 24 is-;designed toprovide the type of radiation, such as ultraviolet radiation or .infrared radiation, which is desired, and thedetectorunit is designed to-convert such radiation into anoutput representativethereof. For example, bolometersform asuitable detector unit for infrared radiation, and a suitable detector unit for ultraviolet radiation.

It will be noted that the photoelectric cells27 are connected-in opposition, and that the output of these' photoelectric cells appears across'two leads 28 and 29. Lead 29 is connected to a center tap on a primary winding of an input-transformer 30a forming apart of an ampli-" fier 30. The end terminals of this primary winding'are -connected, to fixedcontact points of a vibratoryinterrup- 'ter-31, the reed of which is connected to the common "terminal of a two-position switch 32.- Onefixed contact of'switch 32 is'connected to lead 28 while the other fixed contact is connected through a battery 33 and a fixed resistance 34 to the lead 29. i Withswitch 32 in its upper position, as shown, leads -28 and 29 are connected through the interrupter 31 to the input circuit of the amplifier so that an-alternating input voltage is produced which is representative of the relative amounts of radiation impinging upon the photoelectric cells 27. With switch 32 in its lower position, the photoelectric cells 7 are disconnected from the ampli- 'fier input circuit, and a constant voltage is applied thereto by the battery 33.

l The output circuit of the amplifier 30 is connected to a'servomotor 36 which is mechanicallyconnected, as by a cam and cam follower, to the rotatable assembly 25.

"Thus,- motor 36 rotates assembly 25 until the amount of-radiation falling upon the photoelectric cells 27 ,is balanced, and the position of motor 36and assembly 25 is representative of the beam deflection caused by the passage thereof through the standard and sample fluids, i.e.-, of the difference in refractive index of these fluids and the composition of' the test material.

Themotor 36 is also mechanically connected to the contactor. of apotentiometer 37, .a fixed. direct voltage :beingfs'upplied across the fixed terminals of this unit from 'a direct current source 37a.- one' fixed terminal of potentiometer 37 are connected, respectively, to the input leads of arecorder -38 so that this unit records therefractiveindex or'composition of the sample material, as indicated by the" position of motor 36.

As previously explained, the sample inlet pipe -19 is connectedto bothsample conduits 18a and 18b through ,which thefiuid .to be analyzed flows from the columns 10a and 10b; respectively. Flow of fluid-through conduits 18a and 18b is controlled by the respective sole- .noid .-valves 40a and 40b, the energizing windings of which aresupplied with current from a set 41- of'terminals=through a timer or cam switch 42. The timer inpludesa-motor 42a supplied with power from terminals 42b as controlled by aswitch 420. A shaft 42a. is driven ,by .themotor and carries a cam-42s which alternately closes two contact sets 42) and 42: thereby alternately and-cyclically opening solenoid valves 40a and 40b to permit-fluid to. pass to the sample cell alternately from the two crystal separation units. Pilot lights 44a and- 44b-are connected in parallel, re-

spectively, with the solenoids of valves 40a and 40b to indicate which -.valve.is operating. A pair of time delay units or; relays-45a and 45b have 'heater elements 46 conflnected in parallel withrthe respective solenoids of' valves 40a and 40b. The time delay relays also have normally The contactorand I closed contact sets 47a and 47b, respectively, which are connected in series with the respective operating windings of a pair of auxiliary relays 48a and 48b, the series combinations of relay winding and normally closed contact sets being connected in parallel with the respective solenoids of valves 4021 and 40b. The contact sets 47a, 47b. each have aspark suppressor connected in parallel therewith, each suppressor including a resistance 49 and a condenser 50. i The-relays 48a, 48b each have a set of normally open -contacts which areconnected in.parallel. Closure of either contact set short circuits input leads 51 and 52 leading to the input terminals of the recorder 38.

In operation, timer 42 passes through repeated cycles 5 of operation, thereby alternately opening valves 40a and 40b. During each cycle, there is a period of analysis of fluid passing through line 18a and a period of analysis of fluid passing through line 18b. As these streams pass successively through the sample cell a, their composi- 20 tion is indicated by recorder 38 by virtue of the action L of 'servomotor 36,'-rotatable assembly and potentiom- ---'eter 37."'The composition of the sample material is, acchrdinglygindicateduponthe moving recorder chart or niediUmPFig'ure-Z, inan alternating manner, the compositioiiofthefluidpassing through line 18a being indicated"byportions--55a of the chart, and the composition of thefluid'passing through'line 18b being indicated by *po'rtion s' 55b of the chart. "It is a'feature of the invention that the cam 42e of timer 742 is" so shaped 'that'one of the recording periods is longer; to -a slight butnoti'ceable extent, than the other Tecordingperiod. Accordingly, one set 55a of traces "upon'nhe recorder chart'is longer than the other set 55b, thus ehablingthe operator to determine at a glance which stream is represented by any part of' the line on the-chart.

'Turtherj as each" valve'40aor b is opened at the "beginningofan analyzing period, current is supplied "through the associated contacts 47 to the associated relay48, thereby energizing one of these relays, and closing one set of relay contacts to short circuit the amplifier "'input'lead's. This causes the pen on the recorder chart to move to zero, as indicatedby'the lines 550 in Figure 2; thereby forming an index mark on the chart each time analysis of a different stream is initiated.

Closure of the circuit through one of the solenoid valves also closes a circuit through the associated heater "element '46, which causes the associated contact set 47a to op'enafter a short predetermined period, as determined 'by the setting of the time delay unit. Thereupon, the associated relay 48 is deenergized and its contacts are opened thereby opening the short circuit existing at the recorder input terminals; At this time, the recorder pen returns to its normal recording position a, 55b and 55 indicates the composition of the fluid under analysis during the remainder of the analysis period.

Iniaddition to providing a short index mark on the 'chart at the beginning ofveach analysis period, the desc'ribed deactivation of the recorder is advantageous for, during this short interval, the new material to be analyzed 'passes through conduit 19 and reaches the sample cell 1012' before-operation of the recorder is initiated to indicate the' composition of this new test material.

It will be evident, therefore, that we have achieved the 5 "objects ofthe invention in providing an instrument well suited forthe'analysis of multicomponent streams, the recorder chart'permitting the stream under analysis to be accurately and rapidly identified, and having an index rriarlfiatthe'beginning'of each analysis period. More- 7o1fove'r, the instrument is'adapted to indicate the composi- .'tion of one of the feeddisplaced liquid, product or heat- ?ingjh'ediunij streamsof a crystal separation operation,

)5 "particularly one involving a plurality of distinct separation units, to the end that. proper and efficient process control can be maintained.

Aha, in accordance with the invention,the described difi'erential refractometer can advantageously be used to control a crystal separation process, even where a single instrument is used for this purpose in conjunction with a plurality of separation units. To this end, we have shown the system applied to the automatic control of two columns to regulate the rate of flow of product from the separation units in accordance with the composition of the product stream. It will be understood, of course, that under diflerent conditions the composition of other streams can be determined and other process variables can be regulated than the rate of'flow of product. For instance, the feed rate can be regulated, or the rate of withdrawal of displaced liquid, or even the quantity or temperature of the heating medium supplied to. the coils 13 in a manner which will become obvious upon reading the following description.

In the described embodiment, an additional cam 60 is provided on cam shaft 42d, and this cam actuates contact .sets 60a and 6012. Contact set 60a is closed a predetermined period after the closure of contact 42f, the delay period being allowed to permit fluid from line 18a to reach the sample cell 20a before the control period is :started. Further, contacts 60a open at the same time :as contacts 42 Similarly, contact set 60b closes a predetermined interval after the closure of contact set 42g and opens at the same time as contact set 42q.

Contact sets 60a and 60b are operative to connect the voltage applied to the recorder input terminals to an electronic rate of flow controller 61 when valve 40a is open and to an electronic rate of flow controller 62 when valve 40b is open. The controllers 61 and 62 have the usual flow-sensing taps in the lines 15a and 15b, respectively, and they control valves 64a and 6412, respectively, so as to maintain the product of the two columns at a constant refractive index, i.e., composition. The controllers remain at the position they reach at the end of a control cycle until the beginning of the next control cycle and, in commercial units, the product composition changes with suflicient slowness to permit efficient operaf tion, even though the actual control is being effected during slightly less than half the time of operation.

While the invention has been described in connection with a present, preferred embodiment thereof, it is to be understood that this description is illustrative only and is not intended to limit the invention.

We claim:

1. In a separation process utilizing crystals wherein, in each of a plurality of separation zones, a feed stream including crystalline and liquid material is fed to the separation zone, a liquid stream is displaced and separated from the feed stream, and crystals are melted to form a product stream by exchange with a stream of heating medium, the steps which comprise withdrawing a first portion of a stream from one of said separation zones, forming a beam of radiation, producing an output representative of the deflection of a terminal part of said beam, passing said first portion through said beam to cause a deflection thereof representative of the index of refraction of said first portion, the output thereby produced representing the stream composition, withdrawing a second portion of a stream from another separation zone, passing said second portion through said beam after interrupting the flow oftsaid first portion therethrough, whereby a beam deflection is produced which is representative of the composition of said second portion, and thereafter alternately and cyclically passing portions from said separation zones through said beam.

2. A method in accordance with claim 1 wherein said first portion is passed through the beam for a longer period, during each cycle of operation, than is said second portion.

3. In a separation process utilizing crystals wherein, in each of a plurality of separation zones, a feed stream including crystalline and liquid material is fed to the separation zone, a liquid stream is displaced and sepa rated from the feed stream, and crystals are melted to form a product stream, the steps which comprise passing a beam of visible light through a standard fluid to cause a deflection thereof, producing an output representative of beam deflection, recording said output upon a moving medium, cyclically withdrawing a steam, in succession, from each separation zone to provide, during each cycle, at least a first analyzing period and a second analyzing period, and passing the'withdrawn streams during the respective analyzing periods through said radiation beam to further deflect same. i

4. In a separation process utilizing crystals wherein, in each of a plurality of separation zones, a feed stream including crystalline and liquid material is fed to a separation zone, a liquid stream is displaced and separated from the feed stream, andcrystals are vmelted'to form a product stream, the steps which comprise passing a beam of visible light through a standard fluid to cause a deflection thereof, producing an. output representative of beam deflection, recording said output upon a moving medium, cyclically withdrawing a stream, in succession, from each crystal separation zone to provide, during each cycle, at least a first analyzing period and a. second analyzing period, said .first analyzing period being of longer duration than said second analyzing period, passing the withdrawn streams, during the respective analyzing periods, through said radiation beam to further deflect same, and producing an:index mark upon said medium at the beginning of each analyzing period.

5. An analyzer for. analyzing a plurality of sample streams to be analyzed which comprises, in combination,

a radiation source, a radiation detector. unit. disposed in the beam of radiation from said source, a recorder having a set of input terminals, means responsive to radiation impinging on said detector unit for applying to said recorder input terminals a signal representative of the radiation impinging upon said detector unit, a first line arranged to deliver a first sample stream into the beam ofradiation, a first solenoid valve controlling the flow of stream through said line, a second line arranged to deliver another sample material into the beam of radiation, a second solenoid valve controlling the. flow of material through said second line, first and second relays each having an operating winding and a set of contacts connected in circuit with the input terminals of said recorder, each contact set being arranged to apply a signal to the recorder upon energization of the relay controlling the set of contacts, a timer arranged to alternately energize said solenoid valves, first and second time delay devices connected in circuit with the respecrelays, said connections being arranged so that each relay is energized uponenergization of the time delay device connected thereto and de-energized a predetermined time thereafter. I

6. An analyzer for analyzing a plurality of sample streams to be analyzed which comprises, in combination, a radiation source, a radiation detector unit disposed in the beam of radiation from said source, a recorder having a set of input terminals, means responsive to radiation impinging on said detector unit for. applying to said recorder input terminals a signal representative of the radiation impinging upon said detector unit, a first line arranged to deliver a first sample stream into the beam of radiation, a first solenoid valve controlling the flow of material through said line, a second line arranged to deliver another sample stream into the beam of radiation, a second solenoid valve controlling the flow of material through said second line, first and second relays each having an operating winding and a set of contacts connected in circuit with the input terminals of said recorder,

eachcontaet set being arranged t o 'apply a signal the recorderupon energizationiof the relay controllingthe set of contacts, a timer arranged to cyclically and alternatelyenergize said tsblenoidvalves, first and second time delay devices connected in circuit with the respective solenoid valves and energized by said timer at the time'of energization of the respective solenoid valves connected thereto; connections between said time delay devices and the operating windings .of the respective re laysQsaidconnectiohs being anangedfso that each'relay is energized upo'n energization ofthe timedelay device connected thereto-and deehergized a predetermined time theieaftei, the -time of "energization of one of said solenoid valves during each'cycle being greater'than the time ofenergization of the other; solenoid valve.

7. A multistream differential refractometer which comprises, in combination, a. photoelectric cell detector unit,

a source ofvisible light arranged to direct a beam of radiation upon said detector unit, a recorder connected to and energized by said detector unit, timing means arranged to cyclically' admit, in succession, a plurality of sample streams tothe path of said beam to'provide a plurality of analysis periods-during each cycle, whereby said beam is deflected and the recorder produces an output representative of beam deflection, and means energized by' said timing means to apply '-a signal to said recorder at the be'ginning-of each period of analysis,

whereby an index mark is made by the recorder signifying the beginning of each analysis period. h

8. A multistream diiierential' refractometer whichcomprises, in combination, fa photoelectric cell detector unit including a pair of spaced photoelectric cells, a

source of visible light'arranged to direct a beam of radiation upon said photoelectric cells, a prism arranged in said beam to disperse same and-cause it to fall-upon both photoelectriccells, 'motor-driven means to' deflect said beam, a cell assembly inthe' path of said beam including a standard cell and a samplecell, a plurality of lines arranged to deliver different sample streams to said sample cell, solenoid valves controlling the flow of fluid through the respective lines, a timedelay relay connected'in parallel with'each solenoid valve a plurality of auxiliary relays having their operating windings connected in circuit with the respective time delay relays to the end that the auxiliary relaysnare energized upon the'energization of the respectiv e time delay relays and w deenergized a "short period thereafter, each auxiliaryrelay having a set of c'ontacts controlled thereby, a timer, means controlled by said-timer to alternately and cyclically open saidsolenoidvalves and energize the time delay relays connected thereto, a recorder havinga set of input terminals, a potentiometer connected to said input terminals to provide an input signal for said re-- corder, leads connecting said input terminals to the contacts of each auxiliary relay whereupon energization of each auxiliary relay short circuits the recorder input 1 terminals, a mechanical coupling connecting said motordriven'means to saidpotentiometer, an alternating current-amplifier having its output circuit connected to said motormeans to energize same, and means including a vibratory interrupter for connecting said photoelectriccell'detector unit to theinput of said amplifier.

9. A multistream difierential refractometer which comprises, in combination; a photoelectric cell detector unit,

a source'of visible'light arranged 'todirect a beam of radiation upon saidunit, motor-driven means to deflect said beam, a cell assembly in the path of said beam in cluding -astandardcelland a sample cell,- a plurality of f lines arranged-to deliver different sample streams to said]: sample cell, solenoid valves controlling the flow of fluid through the respective lines, a time delay unit for each f. valve; a timer, means controlled by said timer to alter-.

nately-and cyclically open said solenoid valves and energize the -time delay units corresponding thereto, a recorder, a potentiometer connected to the input of said recorder to provide-an input signahmeans connecting said-recorder to said time delay units to apply a signal. thereto during the delayperiod of each such unit, a

mechanical connection between said motor-driven means and saidpotentiometer an alternating current amplifier: having its output circuit connectedto said motor meansto energize same,'and means including a vibratory inter-.

rupter for connecting said detector unit to the input of said amplifier.

10. 'In a control system, for a plurality of separation.

units utilizing crystals wherein, in each of a plurality of separation-zones, a feed stream-including crystalline and liquid material is fed-to the separation zone, a liquid stream is displaced and separated from the feed stream,

and crystalsare melted to form a product stream, in combination, a difierential refractometer, means including a timer for-cyclicallyfeeding samples of the product streams of the plurality of separation zones, in succession, to :said refractometer, electrically actuated-controllers alranged to regulate=the rate of withdrawal of product from the-respective separation zones, and means actuated by said timer for feeding the output of said refractometer.

to the controller of the rate of product withdrawal of that fed to said refractometer.

11. A multistream diflFerential refractometer which comprises, incombination, a photoelectric cell detector s eparation zone from which the sample material is being unit,'a source of visible light arranged to direct a beam of radiation upon said unit, motor-driven means to deincluding a standard cell and a sample cell, a plurality of lines "arranged to deliver different sample streams to flect said beam, a cell assembly in the path of said beam said sample cell, valves controllingthe flow of fluid throughthe respective lines, "a time delay unit for each valve, a timer, means: controlleduby said timer to alternately and cyclically open said valves and energize the time delay units corresponding thereto, means connecting said recorderto saidtime delay units to apply a signal thereto during .the'delay periodofeach such unit, and

means connecting-said detector unit to the input of said recorder to producea signal representative of the amount of light'falling uponsaid photoelectric cell detector unit.

References Cited in the file of this patent UNITED STATES PATENTS UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION" Patent No, 2,890,617 June 16, 1959 Dale E, Lupfer et a1,

It is hereby certified that error appears in the printed -specification of the above numbered patent requiring correction and that -theysaid Letters Patent should readas corrected below.

Column 6, line '7, for "steam" read stream line 41, for "stream" read material line 42, for "material" read stream Signed and sealed this 23rd day of February 1960.,

(SEAL) Attest:

KARL H, AXLINE Attesting Officer ROBERT C. WATSON Commissioner of Patents 

